C# Regex Issue “unrecognized escape sequence”

Question

I have an issue with the regular expressions I\'m using but don\'t know how to continue with them. I get the error \"unrecognized escape sequence\".

I am trying to l

Answer 1

The problem is not the regex, but the string. Before compiling it to a regex with the call to IsMatch(), the text you enter is still a normal string and it must obey the language rules.

\d in your language is not a recognized escape sequence, hence the error. You can either double backslashes (\ is the escape sequence to get a ) or, as Blindy pointed out, you can prefix your constant strings with a @, telling the compiler that it should not try to interpret anything looking like an escape sequence to it.

Answer 2

Add an additional '\' to unescape the escape. When it's processed it will then be interpreted in the manner you intended.

Answer 3

Use @ to make the strings no longer use the escape character \:

string regexPattern1 = @"^(\d{3}\.){2}\d{4}$";
string regexPattern2 = @"^((\(\d{3}\) ?)|(\d{3}-))?\d{3}-\d{4}$";

As a side note, I think you want the two ifs at the end to be a single if with an or (||) between the two conditions.